scholarly journals Electric fields and valence-band offsets at strained [111] heterojunctions

1997 ◽  
Vol 55 (19) ◽  
pp. 13080-13087 ◽  
Author(s):  
S. Picozzi ◽  
A. Continenza ◽  
A. J. Freeman
Keyword(s):  
Valence Band ◽  
Electric Fields ◽  
Band Offsets

Absorption and optical conduction in InSe/ZnSe/InSe thin film transistors

2016 ◽  
Vol 09 (02) ◽  
pp. 1650019 ◽  
Author(s):  
S. E. Al Garni ◽  
A. F. Qasrawi
Keyword(s):  
Thin Film ◽  
Valence Band ◽  
Electric Fields ◽  
Optical Conductivity ◽  
Thin Film Transistor ◽  
Free Carrier Absorption ◽  
Band Offsets ◽  
Dielectric Spectra ◽  
X Ray ◽  
Alternating Electric Fields

In this work, (n)InSe/(p)ZnSe and (n)InSe/(p)ZnSe/(n)InSe heterojunction thin film transistor (TFT) devices are produced by the thermal evaporation technique. They are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy and optical spectroscopy techniques. While the InSe films are found to be amorphous, the ZnSe and InSe/ZnSe films exhibited polycrystalline nature of crystallization. The optical analysis has shown that these devices exhibit a conduction band offsets of 0.47 and valence band offsets of 0.67 and 0.74[Formula: see text]eV, respectively. In addition, while the dielectric spectra of the InSe and ZnSe displayed resonance peaks at 416 and 528[Formula: see text]THz, the dielectric spectra of InSe/ZnSe and InSe/ZnSe/InSe layers indicated two additional peaks at 305 and 350[Formula: see text]THz, respectively. On the other hand, the optical conductivity analysis and modeling in the light of free carrier absorption theory reflected low values of drift mobilities associated with incident alternating electric fields at terahertz frequencies. The drift mobility of the charge carrier particles at femtoseconds scattering times increased as a result of the ZnSe sandwiching between two InSe layers. The valence band offsets, the dielectric resonance at 305 and 350[Formula: see text]THz and the optical conductivity values nominate TFT devices for use in optoelectronics.

scholarly journals Built-in electric fields and valence band offsets in InN/GaN(0001) superlattices: First-principles investigations

2011 ◽  
Vol 109 (8) ◽  
pp. 083721 ◽  
Author(s):  
C. C. Shieh ◽  
X. Y. Cui ◽  
B. Delley ◽  
C. Stampfl
Keyword(s):  
Valence Band ◽  
Electric Fields ◽  
First Principles ◽  
Band Offsets

scholarly journals Investigation of Band Alignment for Hybrid 2D-MoS2/3D-β-Ga2O3 Heterojunctions with Nitridation

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Ya-Wei Huan ◽  
Ke Xu ◽  
Wen-Jun Liu ◽  
Hao Zhang ◽  
Dmitriy Anatolyevich Golosov ◽  
...  
Keyword(s):  
Valence Band ◽  
Transition Metal Dichalcogenides ◽  
Three Dimensional ◽  
Optoelectronic Devices ◽  
Band Alignment ◽  
Band Offsets ◽  
Group Iii ◽  
Nanoelectronic Devices ◽  
Metal Dichalcogenides ◽  
Band Alignments

AbstractHybrid heterojunctions based on two-dimensional (2D) and conventional three-dimensional (3D) materials provide a promising way toward nanoelectronic devices with engineered features. In this work, we investigated the band alignment of a mixed-dimensional heterojunction composed of transferred MoS2 on β-Ga2O3($$ 2- $$2-01) with and without nitridation. The conduction and valence band offsets for unnitrided 2D-MoS2/3D-β-Ga2O3 heterojunction were determined to be respectively 0.43 ± 0.1 and 2.87 ± 0.1 eV. For the nitrided heterojunction, the conduction and valence band offsets were deduced to 0.68 ± 0.1 and 2.62 ± 0.1 eV, respectively. The modified band alignment could result from the dipole formed by charge transfer across the heterojunction interface. The effect of nitridation on the band alignments between group III oxides and transition metal dichalcogenides will supply feasible technical routes for designing their heterojunction-based electronic and optoelectronic devices.

A Purely Spectroscopic Technique for Determining Energy Band Offsets in Quantum Wells

1991 ◽  
Vol 240 ◽  
Author(s):  
Emil S. Koteies
Keyword(s):  
Quantum Wells ◽  
Valence Band ◽  
Accurate Determination ◽  
Energy Difference ◽  
Spectroscopic Technique ◽  
Band Offsets ◽  
Band Energy ◽  
Semiconductor Quantum Wells ◽  
Sensitive Function

ABSTRACTWe have developed a novel experimental technique for accurately determining band offsets in semiconductor quantum wells (QW). It is based on the fact that the ground state heavy- hole (HH) band energy is more sensitive to the depth of the valence band well than the light-hole (LH) band energy. Further, it is well known that as a function of the well width, Lz, the energy difference between the LH and HH excitons in a lattice matched, unstrained QW system experiences a maximum. Calculations show that the position, and more importantly, the magnitude of this maximum is a sensitive function of the valence band offset, Qy, which determines the depth of the valence band well. By fitting experimentally measured LH-HH splittings as a function of Lz, an accurate determination of band offsets can be derived. We further reduce the experimental uncertainty by plotting LH-HH as a function of HH energy (which is a function of Lz ) rather than Lz itself, since then all of the relevant parameters can be precisely determined from absorption spectroscopy alone. Using this technique, we have derived the conduction band offsets for several material systems and, where a consensus has developed, have obtained values in good agreement with other determinations.

Effect of Deposition Method on Valence Band Offsets of SiO2 and Al2O3 on (Al0.14Ga0.86)2O3

2018 ◽  
Vol 8 (7) ◽  
pp. Q3001-Q3006 ◽  
Author(s):  
Chaker Fares ◽  
F. Ren ◽  
David C. Hays ◽  
B. P. Gila ◽  
S. J. Pearton
Keyword(s):  
Valence Band ◽  
Deposition Method ◽  
Band Offsets

Valence band offsets in strained GaAs1−xPx/GaAs heterojunctions

1995 ◽  
Vol 24 (6) ◽  
pp. 713-717 ◽  
Author(s):  
Neal G. Anderson ◽  
Farid Agahi ◽  
Arvind Baliga ◽  
Kei May Lau
Keyword(s):  
Valence Band ◽  
Band Offsets

Chemical bath process for highly efficient Cd-free chalcopyrite thin-film-based solar cells

2000 ◽  
Vol 77 (9) ◽  
pp. 723-729
Author(s):  
A Ennaoui
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Subsequent Development ◽  
Energy Band Diagram ◽  
Buffer Layers ◽  
Band Offsets ◽  
Good Surface

The highest efficiency for Cu(Ga,In)Se2 (CIGS) thin-film-based solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as the chemical bath deposition (CBD). With the aim of developing Cd-free chalcopyrite-based thin-film solar cells, we describe the basic concepts involved in the CBD technique. The recipes developed in our laboratory for the heterogeneous deposition of good-quality thin films of ZnO, ZnSe, and MnS are presented. In view of device optimization, the initial formation of chemical-bath-deposited ZnSe thin films on Cu(Ga,In)(S,Se)2 (CIGSS) and the subsequent development of the ZnSe/CIGSS heterojunctions were investigated by X-ray photoelectron spectroscopy (XPS). The good surface coverage was controlled by measuring changes in the valence-band electronic structure as well as changes in the In4d, Zn3d core lines. From these measurements, the growth rate was found to be around 3.6 nm/min. The valence band and the conduction band-offsets ΔEV and ΔEC between the layers were determined to be 0.60 and 1.27 eV, respectively for the CIGSS/ZnSe interface. The energy-band diagram is discussed in connection with the band-offsets detemined from XPS data. A ZnSe thickness below 10 nm has been found to be optimum for achieving a homogeneous and compact buffer layer on CIGSS with a total area efficiency of 13.7%.PACS No.: 42.70

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